We’re at the San Francisco Design center, blogging Inside Network’s third annual Inside Social Apps conference. Founder of Inside Network Justin Smith sat down with Facebook Director of Software Engineering Cory Ondrejka for a fireside chat called “The Future of Mobile App Discovery on Facebook.”

Ondrejka emphasized the value of building HTML5 apps that users can access from any device and how integrating Open Graph will allow users to share their activity without interrupting gameplay.

Ondrejka revealed that half of Facebook’s mobile traffic comes through the mobile website and the other half comes from native applications. He said that the company spent much of 2011 improving its mobile touch site and integrating web technology in its native applications. For example, the iOS and Android apps now pull News Feed stories directly from m.facebook.com so Facebook’s engineers can push design and backend changes without a software update.

“The trend of wanting the web to work really well is something that’s happening,” Ondrejka said. “It’s incumbent on us to write good code, show good examples and make it easy to integrate.”

Although Ondrejka encouraged HTML5 development for cross-platform access, he acknowledged that some apps will require advanced capabilities that are only possible as native experiences. Still, Facebook’s distribution channels function the same for web and native apps.

“The important thing about our platform at this point is that we want all of these to integrate with Open Graph,” he said.

Because the company filed for an initial public offering last week, Ondrejka was unable to discuss possible plans for advertising apps within Facebook’s mobile experiences. He instead focused on the organic channels that are available to mobile developers: Open Graph activity in News Feed and Timeline, app bookmarks and requests.

Facebook apps can now publish continuously to Timeline and Ticker, which Ondrejka said will improve the gameplay experience. The strategy seems to be increase engagement by making games more enjoyable and organic discovery will follow.

“What Open Graph allows you to do is share in this non-interruptive way without saying ‘Hey, player, stop playing to issue a request’ I hope it opens up game design as broad as on other devices,” he said.

Ondrejka cited Pinterest and Washington Post Social Reader as good examples of how mobile apps can utilize Open Graph for discovery.

We’re at the San Francisco Design center, blogging Inside Network’s third annual Inside Social Apps conference. The final panel of the day focused on how marketers and brands can use social apps to maximize audience engagement.

Joining moderator Josh Constine, of Techcrunch, were Context Optional CEO Kevin Barenblat, Buddy Media Senior VP Carla Bourque, Facebook Page Product Manager Russ Heddleston, Starz Media VP of Digital Media David Katz, Hearsay Social CEO and Starbucks Board Director Clara Shih.

All of the panelists agreed that building mobile experiences and applications is becoming increasingly important for brand marketers. Shih, of Hearsay Social, and Barenblat, of Context Optional, said that developing application experiences that involve the user being physically present at a retail store have potential for both marketers and developers. Bourque, of Buddy Media, said her company’s mobile focus was primarily on enabling social commerce at scale and driving conversions.

While panelists agreed that building applications for mobile will be increasingly important, their take on building Open Graph applications was mixed. Shih, of Hearsay Social noted that for lifestyle brands, Open Graph represents a significant opportunity because of its ability to connect identity to brands and products. For small or local brands and companies, or those outside of the lifestyle space, Open Graph might not be a good fit. The consensus was that developers and marketers should focus on testing new ideas and generating success at a small scale in order to demonstrate impact, and build upon that.

When asked about the future of page tab applications, and whether they will become mobile compatible at some point in the future, Heddleston, of Facebook, did not make any definitive statement. He reinforced the importance of mobile in Facebook’s overall strategy and noted, “We haven’t yet come out with a separate solution for tab applications for mobile, it’s something we’re looking into, and something that would make sense.”

The panelists discussed some of the factors that go into deciding whether businesses should develop custom applications for their page or work with platform templates. The general consensus was that custom development might not be cost-efficient for some companies, but business objectives should ultimately drive the decision. Shih, of Hearsay Social, said that she’s seen a 50-50 split among larger clients — half begin with a template from Hearsay’s app gallery and half are completely custom experiences developed by another digital agency.

As far as brand integration within existing apps, such as popular social games, the panelists emphasized how distribution and engagement are key things brands should look for before spending money on placement. Katz, of Starz Media, said he especially looks for examples of what an app developer has done before and wants to know that a company has delivered results for similar brands in the past.

Facebook Director of Product Management Carl Sjogreen revealed that more than 60 million monthly users engage with mobile applications via Facebook, 320 million times per month since the mobile platform launched in October 2011. Sjogreen shared this statistic during a fireside chat with Founder of Inside Network Justin Smith at the Inside Social Apps conference in San Francisco.

[Update 2/9/12 12:47 p.m. - An earlier draft of this story was unclear that the 60 million users who engage with apps on Facebook's mobile application are monthly active users.]

This means that 60 million users navigate to either mobile web or native applications that integrated with Facebook each month, and these users engage with apps roughly five times per month. With 425 million monthly active users who access the social network via mobile, this also means that roughly 14 percent of Facebook’s mobile users engage with third-party apps directly from the mobile platform. The company has not offered numbers on how many of its 425 million mobile users have smartphone devices that are capable of running third-party Facebook apps.

When asked about the value proposition of HTML5 to application and app developers, Sjogreen said, “We don’t really care whether developers build for mobile web or native apps,” noting that in his view, the decision is not either-or. Instead, Sjogreen made the point that ”The people you want to play with trump whatever the platform the app is on. If your fundmental gameplay revolves around interacting with friends, then being cross platform is really important.”

Many developers face a dilemma. They can develop native apps for iOS and Android, which can include advanced functionality and graphics, but are often more costly and difficult to maintain. Alternatively, developers can build HTML5-compatible mobile web applications, which lack some of the advanced features of native apps, but can accessed on any platform, which significantly reduces development costs and enables all users to access their apps.

Sjogreen’s comments reinforce that Facebook will support all developers, but emphasizes cross-platform compatibility as an increasingly important factor to consider. This makes sense in the context of building social applications where users interact with friends across different platforms and devices. For app distribution and notifications through Facebook to work effectively for users, apps need to be accessible on whichever device an individual is using at the moment they receive a notification or see activity in News Feed or Ticker.

For more coverage of Sjogreen’s fireside chat from Inside Social Apps today, see our liveblog summary here.

U.K. mobile billing and analytics provider Bango announced today it signed a deal “to provide payment services to Facebook.”

The arrangement could be part of an upcoming effort to monetize Facebook’s mobile platform. The social network has 425 million monthly active mobile users but so far does not generate “meaningful” revenue from this area, according to its filing for an initial public offering. Facebook might have tapped Bango to help it process payments for apps, virtual goods or other mobile transactions.

Bango did not reveal the terms of the agreement. Facebook, which is in a mandated “quiet period” after filing for an IPO, did not comment on the partnership.

Bango provides carrier-billing services for Research in Motion and Opera’s app stores. This means mobile users are able to pay for purchases on their phone bills rather than a credit card. Many expect the company will to do the same for Amazon’s App Store for Android, following news of a partnership in December 2011.

Facebook opened its mobile platform to third-party developers in October 2011. It currently uses Boku to process mobile phone payments in HTML5 games like CityVille. This is only possible in the mobile web version of Facebook, not native applications because Apple and Android take 30 percent of in-app transactions on their platforms.

The Financial Times notes that Bango is aligned with Facebook’s movement toward a browser-based mobile platform. Following rumors of Facebook’s “Project Spartan” in June 2011, Bango CEO Ray Anderson wrote:

Bango technology has been optimized for browser deployment, and we see the browser as a great platform to enable truly explosive growth of mobile by making apps less dependent on the handset operating system. If you want to share an app or service with others, it makes more sense to mail or tweet out a link to a web app than to try to get your friends to download apps! It seems like Facebook may have the same vision [...]

A greater percentage of Facebook’s monthly active users became daily active users in recent years as consumers switched to smartphones, according to an analysis of the company’s filing for an initial public offering.

DAU as a percentage of MAU is an important metric to judge “stickiness.” If the company were gaining millions of new users but not maintaining a steady DAU over MAU, it would suggest those users were not finding reasons to return as frequently. In Facebook’s case, the ratio of monthly users returning daily has increased from 44 percent to 57 percent since June 2009. This supports the idea that the social network not only grew in volume but became more engaging. In its IPO prospectus, the company attributes much of this growth to mobile usage.

DAU over MAU grew at its fastest rate between June 30 and Dec. 31, 2009, as smartphone growth took off in the U.S. and Europe. Apple released the iPhone 3GS and Palm released the Pre in June 2009. Motorola introduced the first Droid in October of that year. As millions of consumers purchased smartphones and added Facebook apps, daily engagement accelerated. That period saw faster DAU growth in the U.S. and Europe than it did in Asia and the rest of the world.

The DAU/MAU ratio is not increasing as drastically as it had been, but it continues to grow. DAU as a percentage of MAU increased from 54 percent in December 2010 to 57 percent in December 2011. We can expect this number to keep improving as more users connect to Facebook through mobile apps. Another factor that could encourage more users to engage daily is Open Graph. As more apps and websites integrate Facebook, the social network can increase daily active users without those users visiting the site directly.

It’s unclear how high the percentage will go, but at some point, DAU over MAU will hit a threshold. Investors should keep an eye on this metric to gauge how well Facebook is growing and maintaining interest among its new and existing users.

Facebook has updated its Comments Box plugin to improve functionality for mobile sites, the company announced today on its Facebook + Media page.

People who have already added the Comments Box to their website will find that it is now automatically optimized for mobile. The plugin recognizes when a user is on a mobile device and ignores the width parameter so that comments are displayed at 100 percent. Developers can turn this behavior off by setting the mobile parameter to false and control the width manually. Documentation details are available from Facebook’s developer site.

Previously, websites that integrate Facebook Comments had to resize the box for mobile browsers, but there was not a dedicated mobile version of the plugin. This makes implementation easier for developers, and for users the feature seems to load more quickly.

The social network is strongly promoting its comments plugin as a way for media sites and blogs to improve engagement and reduce spam. We use Facebook Comments on InsideFacebook.com and have written about how the feature can sort comments by relevance and affect a site’s Google search rankings.

Image credit: Facebook + Media

Users can now toggle between page posts and fan posts when visiting page walls on mobile devices. This has long been a feature on the web, but mobile displays showed all wall posts in a single stream. The change allows official posts to be surfaced instantly rather than getting buried by fan posts, which was particularly problematic on mobile screens that only have room to show a few posts at a time.

As Facebook is likely to introduce Sponsored Stories into the mobile stream early this year, we expect it to continue to bring mobile page functionality up to par with that on the website. We discovered Facebook testing a recommendations section on the mobile touch site earlier today. Mobile pages, though, still lack the option for page owners to customize a landing tab. This would be an important feature if pages gain the ability to run mobile ad campaigns.

However, as more users access the social network through their phones, Facebook’s product designers have to decide which features to add to mobile without making the experience too complicated.

The addition of filters on mobile pages is unobtrusive and they function easily. Users can filter posts by tapping “All” or the name of the page just above the wall. It appears the default view on mobile is the same as it is for the website. Page owners can set the default by going to “Edit Page,” “Manage Permissions,” then “Wall Tab Shows” on Facebook.com. Admins cannot edit their pages from the mobile site or apps.

Facebook is testing a recommendation tab for some pages on its mobile touch site. As the company continues to build out its mobile pages with social recommendations and additional information, it could become an alternative to Yelp and other location-based search and review products.

In May, users gained the option to read and write recommendations for locations and any page with an address listed on Facebook. Bringing the feature to mobile devices has been an obvious next step so users can learn what their friends and others think of places nearby.

For now, users can access recommendations from m.facebook.com on touch devices, not the native apps. Users can search for a page by name or browse “Nearby.” At the top of the mobile page is a “More” option, which includes “Recommendation” in a drop-down menu. From there, users can write a recommendation (and adjust their privacy settings for the post) or read reviews from friends and the general public. As on the web, the default view is recommendations from friends.

Recommendations are only enabled for pages that are associated with a location. Any fan page can gain this status by adding an address to its info section, though it is likely Facebook will one day expand recommendations to all pages, including consumer goods, websites and other services.

When recommendations become available in Facebook’s mobile apps, stores and restaurants may start including “Recommend us on Facebook” calls to action at their locations, just as they encourage visitors to review them on Yelp. When users write on a page wall, that post can get quickly buried by more recent posts. Recommendations, however, are displayed separately and can be highly influential to a person’s friends and other users. They also generate a News Feed story which includes a link for a person’s friends to also write a recommendation.

The annual uptick in app downloads and new device activations around Christmas has translated into big mobile gains for Facebook.

During the holidays the social network’s apps climbed to the top of the iOS and Android charts, with both Facebook’s standalone Facebook Messenger app and mobile app seeing noticeable spikes in downloads after Christmas according to AppData. The apps are currently the #1 and #9 most popular free iPhone apps.

The story is similar on Android, and as of today, Facebook Messenger and Facebook for Android are the #1 and #2 most popular free Android apps.

The numbers are a nice cap to the year for Facebook, which focused heavily on its mobile strategy in 2011. Mobile companies accounted for more than half of the acquisitions Facebook made this year and one of those companies — Beluga, which the network bought in March — developed the social network’s standalone messenger app.

Facebook also finished the year with more mobile users than ever, according to Enders Analysis analyst Benedict Evans, who estimates that the social network’s mobile apps now have more than 300 million MAU. Unsurprisingly, the iOS and Android versions of Facebook’s apps account for the lion’s share of its mobile userbase. Approximately 117 million people log in to Facebook’s mobile app every month from an iOS device and 87.8 million from an Android device. In addition, almost half of all Android and iOS device owners have installed Facebook’s mobile apps.

This story originally appeared on our sister site, Inside Mobile Apps.

Facebook’s acquisitions in 2011 suggest a strong focus on mobile technology and talent, as six of the 11 startups acquired this year had previously been working on mobile ventures.

In September, Facebook announced it had 350 million monthly active users accessing its services through mobile devices. This was 100 million more than it had said were active on mobile in March. As the social network introduced a mobile app platform to third-party developers in October, we expect it to continue to build its expertise in this area next year.

Rel8tion – January

The stealth hyper-local mobile advertising startup was acquired and brought into Facebook’s Seattle office. The social network hasn’t yet announced plans to bring ads to its mobile experience, but there have been reports that this could happen before Spring 2012.

Pursuit – February

Facebook hired two of the three founders of this professional network startup that helps employers promote job openings by using their employees’ social networks. So far we haven’t seen Facebook add more professional networking tools, though there are several third-party job apps growing on the platform.

Beluga – March

Five months after Facebook acquired this group messaging startup, the social network released a standalone messaging app that has been one of iOS’ top free apps since it debuted. The success of Messenger could encourage Facebook to develop more standalone apps, for instance one for quick photo-sharing.

Snaptu – March

After partnering with the Israeli startup earlier in the year to bring the app to 2,500 different kinds of mobile devices, Facebook brought the team on presumably to continue to build smartphone-like experiences on basic feature phones.

Recrec – April

This was a talent acquisition, rather than a a traditional acquisition, but most of the founding team of Dogpatch Labs-incubated startup Recrec joined Facebook. Recrec had been developing technology that automatically converted images into HTML and CSS.

Daytum – April

When Facebook hired the two founders of this New York-based startup, we suggested the new employees could help the social network track and visualize activity such as photo uploads, checkins or wall posts. As it turns out, the new monthly and yearly summary boxes on Timeline look a lot like Daytum, which lets people manually enter data such as trips to the gym, films watched or food consumed.

Sofa – June

The social network acquired this Dutch development and design startup for its talent, not its software products, which include Kaleidoscope for tracking differences in text and images, Versions for code version control, and ecommerce platform Enstore.

Digital Staircase – November

Facebook fueled speculation about a possible standalone photo-sharing app when it acquired Digital Staircase, maker of a handful of photo and video editing apps, including MovieCam.

MailRank – November

The social network picked up two former directors of engineering of Second Life-maker Linden Lab in a talent acquisition of MailRank this fall. It did not provide details about what the pair would be working on.

WhoGlue – November

Unlike others, this acquisition was not for talent. Facebook bought Baltimore-based social networking software firm WhoGlue Inc, a company it had sued for patent infringement two years ago. The renamed WhoGlue LLC continues to develop private social networks for its clients.

Gowalla – December

Most recently, Facebook brought Austin-based Gowalla co-founders and other key team members to Palo Alto to work on product and engineering. The social network did not acquire Gowalla technology. The location-based service will be closing sometime in January, according to a blog post by co-founder Josh Williams.

Image credit: Gowalla